@article{AA_2008_20_5_a7,
     author = {A. V. Ustinov},
     title = {On the number of solutions of the congruence $xy\equiv l$ $(\operatorname{mod}q)$ under the graph of a~twice continuously differentiable function},
     journal = {Algebra i analiz},
     pages = {186--216},
     publisher = {mathdoc},
     volume = {20},
     number = {5},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2008_20_5_a7/}
}